Participants who engaged in moderate physical activity (such as brisk walking) and used a computer were 64 percent less likely to have mild cognitive impairment compared with those who did not exercise and did not use a computer.

Mild cognitive impairment is a condition in which people experience noticeable declines in their cognitive function, including memory and language problems, but are still able to perform everyday activities.

"The aging of baby boomers is projected to lead to dramatic increases in the prevalence of dementia," said study researcher Dr. Yonas Geda, a physician scientist with Mayo Clinic in Arizona. "As frequent computer use has becoming increasingly common among all age groups, it is important to examine how it relates to aging and dementia."

However, the study relied on participants to remember how often they had exercised or used a computer in the past year. More studies will be needed that follow people forward in time to confirm the results.

Computers and exerciseSome previous studies have found a link between exercise and a reduced risk of mild cognitive impairment (MCI), while others have linked cognitively stimulating activities, such as reading books, playing games or using a computer, and a reduced risk of mild cognitive impairment. But no studies have examined the combined effects of exercise and computer use.

Geda and his colleagues surveyed 926 people ages 70 to 93 living in Olmsted County, Minn. Participants were asked whether they had engaged in moderate physical activity, such as brisk walking, hiking, aerobics, strength training, yoga or weight lifting, in the past year, and how frequently they participated in the activities. They were also asked about the extent of their computer use.

Participants were examined by a physician to diagnose MCI.

Of the 205 study participants who did not exercise and did not use a computer, 41 (20 percent) showed signs of MCI. Of the 314 who both exercised and used a computer, 20 (6 percent) showed signs of MCI, the study found.

People who either used a computer or exercised experienced some protection against mild cognitive impairment, compared with people who did neither activity, but that finding could have been due to chance, the study said.

The results held even after the researchers took into account factors that could affect cognitive function, such as age, sex, education level, depression and the number of calories they ate in a day.

Protecting the brainThe researchers speculated that people who engage in both physical activity and computer use may be healthier, more disciplined individuals. In other words, these activities could simply be a marker for a healthy lifestyle.

It's also possible these activities benefit the brain directly. Exercise may increase production of growth factors that promote the survival of nerve cells. Computer use, and other mentally stimulating activities, may enhance connections in the brain, making it more resistant to damage, Geda said.

Because the study was conducted in one county, it's not clear whether the results can be generalized to the population as a whole. In addition, a sedentary lifestyle caused by too much computer use may predispose people to health problems, the researchers said.

The study is published in the May issue of the journal Mayo Clinic Proceedings.